<!DOCTYPE html>
<html>
<head>
  <meta charset="UTF-8">
  <title>chapter</title>
  <style>
    canvas {
      background-image:
        linear-gradient(#aaaaaa40 1px, transparent 0),
        linear-gradient(90deg, #aaaaaa40 1px, transparent 0),
        linear-gradient(#aaa 1px, transparent 0),
        linear-gradient(90deg, #aaa 1px, transparent 0);
      background-size: 10px 10px, 10px 10px, 50px 50px, 50px 50px;
      width: 601px;
      height: 401px;
      margin: 10px;
    }
  </style>
</head>
<body>
  <canvas width="601" height="401"  id="canvas"></canvas>
</body>
<script type="module" src="./js/index.js"></script>
</html>